JP6926303B2 - Substrate processing method, substrate processing equipment and recording medium - Google Patents

Description

The present invention relates to a technique for removing a liquid adhering to the surface of a substrate using a processing fluid in a supercritical state.

In the manufacturing process of a semiconductor device that forms a laminated structure of integrated circuits on the surface of a semiconductor wafer (hereinafter referred to as a wafer) that is a substrate, fine dust and a natural oxide film on the wafer surface are removed by a cleaning liquid such as a chemical solution. A liquid treatment step of treating the wafer surface using a liquid is performed.

A method of using a processing fluid in a supercritical state is known when removing a liquid or the like adhering to the surface of a wafer in such a liquid treatment step.

For example, Patent Document 1 discloses a substrate processing apparatus that removes a liquid adhering to a substrate by bringing a fluid in a supercritical state into contact with the substrate. Further, Patent Document 2 discloses a substrate processing apparatus that uses a supercritical fluid to dissolve an organic solvent from above a substrate to dry the substrate.

In the drying process of removing the liquid from the substrate using the processing fluid in the supercritical state, the occurrence of the collapse of the semiconductor pattern formed on the substrate (that is, the pattern collapse caused by the surface tension of the liquid between the patterns) is suppressed. , It is desirable to shorten the processing time as much as possible. In addition, it is desirable to reduce the consumption of the processing fluid used for the drying process as much as possible.

Japanese Unexamined Patent Publication No. 2013-12538 Japanese Unexamined Patent Publication No. 2013-16798

The present invention has been made under such a background, and a substrate capable of performing a drying process of removing a liquid from a substrate using a processing fluid in a supercritical state can be performed in a short time while suppressing the consumption of the processing fluid. It is an object of the present invention to provide a processing apparatus, a substrate processing method, and a recording medium.

One aspect of the present invention is a substrate processing method in which a drying process for removing a liquid from a substrate in a processing container is performed using a processing fluid in a supercritical state, and the treatment in the supercritical state existing in the processing container is performed. The fluid in the processing container is discharged until the inside of the processing container reaches the first discharge ultimate pressure at which the fluid does not vaporize, and then the treatment fluid in the processing container does not vaporize at a pressure higher than the first discharge ultimate pressure. The first treatment step of supplying the treatment fluid into the treatment container until the first supply reaching pressure reaches the inside of the treatment container, and the second discharge arrival where the supercritical state treatment fluid does not vaporize after the first treatment step. The fluid in the processing container is discharged until the inside of the processing container reaches a second discharge ultimate pressure that is different from the first discharge ultimate pressure, and then the fluid is discharged higher than the second discharge ultimate pressure and in the processing container. The present invention relates to a substrate processing method comprising a second processing step of supplying a processing fluid into the processing container until the inside of the processing container reaches a second supply ultimate pressure at which vaporization of the processing fluid does not occur.

Another aspect of the present invention is a substrate having a recess, which is a processing container in which a substrate filled with a liquid is carried into the recess, and a fluid supply unit for supplying a processing fluid in a supercritical state into the processing container. And, the fluid discharge part that discharges the fluid in the processing container, the fluid supply part, and the fluid discharge part are controlled, and the drying process of removing the liquid from the substrate in the processing container is performed using the processing fluid in the supercritical state. A control unit is provided, and the control unit controls the fluid supply unit and the fluid discharge unit, and the inside of the processing container reaches the first discharge ultimate pressure at which the supercritical processing fluid existing in the processing container does not vaporize. The fluid in the processing container is discharged until it becomes, and then the inside of the processing container is filled with the first supply ultimate pressure which is higher than the first discharge ultimate pressure and the processing fluid in the processing container does not vaporize. A second discharge that is different from the first discharge ultimate pressure, which is the first discharge ultimate pressure for supplying the treatment fluid and the second discharge ultimate pressure at which vaporization of the treatment fluid in the supercritical state does not occur after the first treatment step. The fluid in the processing container is discharged until the ultimate pressure reaches the inside of the processing container, and then the inside of the processing container reaches a second supply ultimate pressure higher than the second discharge ultimate pressure and the processing fluid in the processing container does not vaporize. The present invention relates to a substrate processing apparatus that performs a second processing step of supplying a processing fluid into the processing container until the above.

Another aspect of the present invention is a computer-readable record recording a program for causing a computer to perform a substrate processing method in which a drying process for removing a liquid from a substrate in a processing container is performed using a processing fluid in a supercritical state. In the substrate processing method, which is a medium, the fluid in the processing container is discharged until the inside of the processing container reaches the first discharge reaching pressure at which the supercritical state processing fluid existing in the processing container does not vaporize, and then the fluid in the processing container is discharged. The first processing step of supplying the processing fluid into the processing container until the inside of the processing container reaches the first supply ultimate pressure, which is higher than the first discharge ultimate pressure and the vaporization of the processing fluid in the processing container does not occur, and the first After one treatment step, the inside of the processing container is filled with the second discharge ultimate pressure at which the vaporization of the processing fluid in the supercritical state does not occur, which is different from the first discharge ultimate pressure. Is discharged, and then the processing fluid is supplied into the processing container until the inside of the processing container reaches the second supply ultimate pressure, which is higher than the second discharge ultimate pressure and the vaporization of the processing fluid in the processing container does not occur. The present invention relates to a recording medium having a second processing step.

According to the present invention, a drying process for removing a liquid from a substrate using a processing fluid in a supercritical state can be performed in a short time while suppressing the consumption of the processing fluid.

FIG. 1 is a cross-sectional plan view showing the overall configuration of the cleaning treatment system. FIG. 2 is an external perspective view showing an example of a processing container of a supercritical processing apparatus. FIG. 3 is a diagram showing a configuration example of the entire system of the supercritical processing apparatus. FIG. 4 is a block diagram showing a functional configuration of the control unit. FIG. 5 is a diagram for explaining the drying mechanism of IPA, and is an enlarged cross-sectional view simply showing a pattern as a recess of the wafer. FIG. 6 is a diagram showing an example of the relationship between the time in the first drying treatment example, the pressure in the treatment container, and _{the consumption amount of the treatment fluid (CO 2).} FIG. 7 is _{a graph showing the relationship between the CO 2} concentration, the critical temperature, and the critical pressure. FIG. 8 is _{a graph showing the relationship between the CO 2} concentration, the critical temperature, and the critical pressure. FIG. 9 is _{a graph showing the relationship between the CO 2} concentration, the critical temperature, and the critical pressure. FIG. 10 is a diagram showing the time and the pressure in the processing container in the second drying treatment example. FIG. 11 is a cross-sectional view for explaining the state of the IPA liquid-filled on the wafer pattern. FIG. 12 is a diagram showing the time and the pressure in the processing container in the third drying treatment example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. It should be noted that the configuration shown in the drawings attached to the present specification may include parts in which the size, scale, etc. are changed from those of the actual product for the convenience of illustration and comprehension.

[Cleaning system configuration]
FIG. 1 is a cross-sectional plan view showing the overall configuration of the cleaning processing system 1.

The cleaning treatment system 1 is attached to a plurality of cleaning devices 2 (two cleaning devices 2 in the example shown in FIG. 1) that supply a cleaning liquid to the wafer W to perform the cleaning treatment, and the wafer W after the cleaning treatment. A plurality of supercritical processing devices 3 (FIG. 1) for removing a liquid for preventing drying (IPA: isopropyl alcohol in this embodiment _{) by contacting it with a processing fluid in a supercritical state (CO 2: carbon dioxide in this embodiment).} In the example shown in the above, six supercritical processing devices 3) are provided.

In this cleaning processing system 1, the FOUP 100 is mounted on the mounting unit 11, and the wafer W stored in the FOUP 100 is transferred to the cleaning processing unit 14 and the supercritical processing unit 15 via the loading / unloading unit 12 and the delivery unit 13. Delivered. In the cleaning processing unit 14 and the supercritical processing unit 15, the wafer W is first carried into the cleaning device 2 provided in the cleaning processing unit 14 to undergo cleaning treatment, and then the supercritical processing unit 15 is provided. It is carried into the processing device 3 and undergoes a drying process for removing the IPA from the wafer W. In FIG. 1, the code "121" indicates a first transport mechanism for transporting the wafer W between the FOUP 100 and the transfer unit 13, and the code "131" indicates a loading / unloading unit 12, a cleaning processing unit 14, and a supercritical processing unit. A delivery shelf that serves as a buffer on which the wafer W transported to and from 15 is temporarily placed is shown.

A wafer transfer path 162 is connected to the opening of the transfer section 13, and a cleaning process section 14 and a supercritical process section 15 are provided along the wafer transfer path 162. In the cleaning processing unit 14, one cleaning device 2 is arranged so as to sandwich the wafer transfer path 162, and a total of two cleaning devices 2 are installed. On the other hand, in the supercritical processing unit 15, three supercritical processing devices 3 functioning as substrate processing devices for performing a drying process for removing IPA from the wafer W are arranged with the wafer transfer path 162 in between, for a total of three. Six supercritical processing devices 3 are installed. A second transfer mechanism 161 is arranged in the wafer transfer path 162, and the second transfer mechanism 161 is provided so as to be movable in the wafer transfer path 162. The wafer W placed on the delivery shelf 131 is received by the second transfer mechanism 161 and the second transfer mechanism 161 carries the wafer W into the cleaning device 2 and the supercritical processing device 3. The number and arrangement of the cleaning device 2 and the supercritical processing device 3 are not particularly limited, and depend on the number of wafers W processed per unit time, the processing time of each cleaning device 2 and each supercritical processing device 3, and the like. , An appropriate number of cleaning devices 2 and supercritical processing devices 3 are arranged in an appropriate manner.

The cleaning device 2 is configured as a single-wafer type device that cleans the wafers W one by one by, for example, spin cleaning. In this case, while the wafer W is held horizontally and rotated around the vertical axis, the chemical solution for cleaning and the rinse solution for washing away the chemical solution are supplied to the processing surface of the wafer W at an appropriate timing. The wafer W can be cleaned. The chemical solution and rinse solution used in the cleaning device 2 are not particularly limited. For example, the SC1 solution (that is, a mixed solution of ammonia and hydrogen peroxide solution), which is an alkaline chemical solution, can be supplied to the wafer W to remove particles and organic contaminants from the wafer W. After that, deionized water (DIW: DeIonized Water) which is a rinsing liquid can be supplied to the wafer W, and the SC1 liquid can be washed away from the wafer W. Further, a diluted hydrofluoric acid (DHF), which is an acidic chemical solution, is supplied to the wafer W to remove the natural oxide film, and then DIW is supplied to the wafer W to supply the diluted hydrofluoric acid aqueous solution from the wafer W. It can also be washed away.

Then, when the cleaning device 2 finishes the cleaning process with the chemical solution, the rotation of the wafer W is stopped, IPA is supplied to the wafer W as a liquid for preventing drying, and the DIW remaining on the processed surface of the wafer W is replaced with the IPA. .. At this time, a sufficient amount of IPA is supplied to the wafer W, the surface of the wafer W on which the semiconductor pattern is formed is in a state of being filled with IPA, and a liquid film of IPA is formed on the surface of the wafer W. .. The wafer W is carried out from the cleaning device 2 by the second transfer mechanism 161 while maintaining the state in which the IPA is filled with liquid.

The IPA thus applied to the surface of the wafer W plays a role of preventing the wafer W from drying. In particular, in order to prevent the so-called pattern collapse of the wafer W due to the evaporation of the IPA during the transfer of the wafer W from the cleaning device 2 to the supercritical processing device 3, the cleaning device 2 has a relatively large thickness. A sufficient amount of IPA is applied to the wafer W so that the film is formed on the surface of the wafer W.

The wafer W carried out from the cleaning device 2 is carried into the processing container of the supercritical processing device 3 in a state where the IPA is filled with liquid by the second transport mechanism 161 and is dried by the supercritical processing device 3. Is done.

[Supercritical processing equipment]
Hereinafter, the details of the drying treatment using the supercritical fluid performed by the supercritical processing apparatus 3 will be described. First, a configuration example of a processing container into which the wafer W is carried in the supercritical processing apparatus 3 will be described, and then a configuration example of the entire system of the supercritical processing apparatus 3 will be described.

FIG. 2 is an external perspective view showing an example of the processing container 301 of the supercritical processing apparatus 3.

The processing container 301 supports a housing-shaped container body 311 having an opening 312 for loading and unloading the wafer W, a holding plate 316 for holding the wafer W to be processed sideways, and the holding plate 316. In addition, a lid member 315 that seals the opening 312 when the wafer W is carried into the container body 311 is provided.

The container body 311 is a container in which, for example, a processing space capable of accommodating a wafer W having a diameter of 300 mm is formed, and a supply port 313 and a discharge port 314 are provided on the wall portion thereof. The supply port 313 and the discharge port 314 are connected to supply lines provided on the upstream side and the downstream side of the processing container 301 for circulating the processing fluid, respectively. Although one supply port 313 and two discharge ports 314 are shown in FIG. 2, the number of supply ports 313 and discharge ports 314 is not particularly limited.

One wall in the container body 311 is provided with a fluid supply header 317 communicating with the supply port 313, and the other wall in the container body 311 is provided with a fluid discharge header 318 communicating with the discharge port 314. There is. The fluid supply header 317 is provided with a large number of holes, the fluid discharge header 318 is also provided with a large number of holes, and the fluid supply header 317 and the fluid discharge header 318 are installed so as to face each other. .. The fluid supply header 317, which functions as a fluid supply unit, supplies the processing fluid into the container body 311 in a substantially horizontal direction. The horizontal direction referred to here is a direction perpendicular to the vertical direction on which gravity acts, and is usually a direction parallel to the direction in which the flat surface of the wafer W held by the holding plate 316 extends. The fluid discharge header 318, which functions as a fluid discharge unit for discharging the fluid in the processing container 301, guides the fluid in the container body 311 to the outside of the container body 311 and discharges the fluid. The fluid discharged to the outside of the container body 311 via the fluid discharge header 318 was dissolved in the processing fluid from the surface of the wafer W in addition to the processing fluid supplied into the container body 311 via the fluid supply header 317. IPA is included. In this way, the processing fluid is supplied into the container body 311 through the opening of the fluid supply header 317, and the fluid is discharged from the container body 311 through the opening of the fluid discharge header 318. A laminar flow of the processing fluid that flows substantially parallel to the surface of the wafer W is formed in the main body 311.

From the viewpoint of reducing the load that can be applied to the wafer W when the processing fluid is supplied into the container body 311 and when the fluid is discharged from the container body 311, a plurality of fluid supply headers 317 and fluid discharge headers 318 may be provided. preferable. In the supercritical processing apparatus 3 shown in FIG. 3 described later, two supply lines for supplying the processing fluid are connected to the processing container 301, but in FIG. 2, one supply line is used for easy understanding. Only one supply port 313 and one fluid supply header 317 connected are shown.

The processing container 301 further includes a pressing mechanism (not shown). This pressing mechanism plays a role of sealing the processing space by pressing the lid member 315 toward the container body 311 against the internal pressure generated by the processing fluid in the supercritical state supplied into the processing space. Further, a heat insulating material, a tape heater, or the like may be provided on the surface of the container body 311 so that the processing fluid supplied into the processing space can maintain the temperature in the supercritical state.

FIG. 3 is a diagram showing a configuration example of the entire system of the supercritical processing apparatus 3.

A fluid supply tank 51 is provided on the upstream side of the processing container 301, and the processing fluid is supplied from the fluid supply tank 51 to the supply line for circulating the processing fluid in the supercritical processing apparatus 3. A distribution on / off valve 52a, an orifice 55a, a filter 57, and a distribution on / off valve 52b are sequentially provided between the fluid supply tank 51 and the processing container 301 from the upstream side to the downstream side. The terms of the upstream side and the downstream side referred to here are based on the flow direction of the processing fluid in the supply line.

The flow on / off valve 52a is a valve that adjusts the on / off of the supply of the processing fluid from the fluid supply tank 51. Do not allow the processing fluid to flow. When the distribution on / off valve 52a is in the open state, for example, a high-pressure processing fluid of about 16 to 20 MPa (megapascal) is supplied from the fluid supply tank 51 to the supply line via the distribution on / off valve 52a. The orifice 55a plays a role of adjusting the pressure of the processing fluid supplied from the fluid supply tank 51, and the processing fluid whose pressure is adjusted to, for example, about 16 MPa is circulated in the supply line on the downstream side of the orifice 55a. Can be done. The filter 57 removes foreign matter contained in the processing fluid sent from the orifice 55a, and causes a clean processing fluid to flow downstream.

The distribution on / off valve 52b is a valve that adjusts the on / off of the supply of the processing fluid to the processing container 301. The supply line extending from the distribution on / off valve 52b to the processing container 301 is connected to the supply port 313 shown in FIG. 2, and the processing fluid from the distribution on / off valve 52b is the supply port 313 and the fluid supply header shown in FIG. It is supplied into the container body 311 of the processing container 301 via 317.

In the supercritical processing apparatus 3 shown in FIG. 3, the supply line is branched between the filter 57 and the distribution on / off valve 52a. That is, from the supply line between the filter 57 and the distribution on / off valve 52b, the purging device 62 is connected to the processing container 301 via the distribution on / off valve 52c and the orifice 55b, the distribution on / off valve 52d, and the check valve 58a. The supply line connected to the outside and the supply line connected to the outside via the distribution on / off valve 52e and the orifice 55c are branched and extended.

The supply line connected to the processing container 301 via the flow on / off valve 52c and the orifice 55b is an auxiliary flow path for supplying the processing fluid to the processing container 301. For example, when a relatively large amount of processing fluid is supplied to the processing container 301, the distribution on / off valve 52c is adjusted to the open state, and the pressure is adjusted by the orifice 55b, as in the initial supply of the processing fluid to the processing container 301. The processed fluid can be supplied to the processing container 301.

The supply line connected to the purge device 62 via the flow on / off valve 52d and the check valve 58a is a flow path for supplying an inert gas such as nitrogen to the processing container 301, and is a flow path from the fluid supply tank 51 to the processing container 301. It is utilized while the supply of processing fluid is stopped. For example, when the processing container 301 is filled with an inert gas to maintain a clean state, the flow on / off valve 52d and the flow on / off valve 52b are adjusted to the open state, and the inert gas sent from the purge device 62 to the supply line is released. It is supplied to the processing container 301 via the check valve 58a, the circulation on / off valve 52d, and the circulation on / off valve 52b.

The supply line connected to the outside via the flow on / off valve 52e and the orifice 55c is a flow path for discharging the processing fluid from the supply line. For example, when the power of the supercritical processing device 3 is turned off, the distribution on / off valve 52e is opened when the processing fluid remaining in the supply line between the distribution on / off valve 52a and the distribution on / off valve 52b is discharged to the outside. Adjusted, the supply line between the distribution on / off valve 52a and the distribution on / off valve 52b is communicated to the outside.

A distribution on / off valve 52f, an exhaust adjustment valve 59, a concentration measurement sensor 60, and a distribution on / off valve 52g are sequentially provided on the downstream side of the processing container 301 from the upstream side to the downstream side.

The distribution on / off valve 52f is a valve that adjusts the on / off of the discharge of the processing fluid from the processing container 301. The distribution on / off valve 52f is adjusted to the open state when the processing fluid is discharged from the processing container 301, and the distribution on / off valve 52f is adjusted to the closed state when the processing fluid is not discharged from the processing container 301. The supply line extending between the processing container 301 and the distribution on / off valve 52f is connected to the discharge port 314 shown in FIG. The fluid in the container body 311 of the processing container 301 is sent toward the distribution on / off valve 52f via the fluid discharge header 318 and the discharge port 314 shown in FIG.

The exhaust adjustment valve 59 is a valve that adjusts the amount of fluid discharged from the processing container 301, and can be configured by, for example, a back pressure valve. The opening degree of the exhaust adjustment valve 59 is adaptively adjusted under the control of the control unit 4 according to the desired amount of fluid discharged from the processing container 301. In the present embodiment, as described later, the process of discharging the fluid from the processing container 301 is performed until the pressure of the fluid in the processing container 301 reaches a predetermined pressure. Therefore, the exhaust adjustment valve 59 adjusts the opening degree so as to shift from the open state to the closed state when the pressure of the fluid in the processing container 301 reaches a predetermined pressure, and adjusts the opening degree of the fluid from the processing container 301. Emissions can be stopped.

The concentration measurement sensor 60 is a sensor that measures the IPA concentration contained in the fluid sent from the exhaust adjustment valve 59.

The distribution on / off valve 52g is a valve that adjusts the on / off of the discharge of the fluid from the processing container 301 to the outside. When the fluid is discharged to the outside, the flow on / off valve 52 g is adjusted to the open state, and when the fluid is not discharged, the flow on / off valve 52 g is adjusted to the closed state. An exhaust adjustment needle valve 61a and a check valve 58b are provided on the downstream side of the distribution on / off valve 52g. The exhaust adjustment needle valve 61a is a valve that adjusts the amount of fluid discharged to the outside via the distribution on / off valve 52g, and the opening degree of the exhaust adjustment needle valve 61a depends on the desired amount of fluid discharged. It will be adjusted. The check valve 58b is a valve that prevents the backflow of the discharged fluid, and plays a role of reliably discharging the fluid to the outside.

In the supercritical processing device 3 shown in FIG. 3, the supply line is branched between the concentration measurement sensor 60 and the distribution on / off valve 52 g. That is, from the supply line between the concentration measurement sensor 60 and the distribution on / off valve 52g, a supply line connected to the outside via the distribution on / off valve 52h, a supply line connected to the outside via the distribution on / off valve 52i, and a distribution on / off. The supply line connected to the outside via the valve 52j is branched and extends.

The distribution on / off valve 52h and the distribution on / off valve 52i are valves that adjust the on / off of the discharge of the fluid to the outside, similarly to the distribution on / off valve 52g. An exhaust adjustment needle valve 61b and a check valve 58c are provided on the downstream side of the distribution on / off valve 52h to adjust the amount of fluid discharged and prevent the backflow of the fluid. A check valve 58d is provided on the downstream side of the distribution on / off valve 52i to prevent backflow of fluid. The flow on / off valve 52j is also a valve that adjusts the on / off of the discharge of the fluid to the outside. An orifice 55d is provided on the downstream side of the flow on / off valve 52j, and the fluid flows from the flow on / off valve 52j to the outside via the orifice 55d. Can be discharged. However, in the example shown in FIG. 3, the destination of the fluid sent to the outside via the distribution on-off valve 52g, the distribution on-off valve 52h, and the distribution on-off valve 52i, and the destination of the fluid sent to the outside via the distribution on-off valve 52j. Is different. Therefore, it is possible to send the fluid to a recovery device (not shown) via, for example, the flow on / off valve 52 g, the flow on / off valve 52h, and the flow on / off valve 52i, while discharging the fluid to the atmosphere through the flow on / off valve 52j.

When the fluid is discharged from the processing container 301, one or more of the flow on / off valve 52 g, the flow on / off valve 52h, the flow on / off valve 52i, and the flow on / off valve 52j are adjusted to the open state. In particular, when the power of the supercritical processing device 3 is turned off, the distribution on / off valve 52j is adjusted to the open state so that the fluid remaining in the supply line between the concentration measurement sensor 60 and the distribution on / off valve 52g is discharged to the outside. May be good.

A pressure sensor for detecting the pressure of the fluid and a temperature sensor for detecting the temperature of the fluid are installed at various points on the above-mentioned supply line. In the example shown in FIG. 3, a pressure sensor 53a and a temperature sensor 54a are provided between the flow on / off valve 52a and the orifice 55a, and a pressure sensor 53b and a temperature sensor 54b are provided between the orifice 55a and the filter 57. A pressure sensor 53c is provided between the flow on / off valve 52b and the flow on / off valve 52b, a temperature sensor 54c is provided between the flow on / off valve 52b and the processing container 301, and a temperature sensor 54d is provided between the orifice 55b and the processing container 301. It is provided. Further, a pressure sensor 53d and a temperature sensor 54f are provided between the processing container 301 and the distribution on / off valve 52f, and a pressure sensor 53e and a temperature sensor 54g are provided between the concentration measurement sensor 60 and the distribution on / off valve 52g. Further, a temperature sensor 54e for detecting the temperature of the fluid in the container body 311 inside the processing container 301 is provided.

Further, the heater H is provided at an arbitrary place where the processing fluid flows in the supercritical processing apparatus 3. In FIG. 3, the supply line on the upstream side of the processing container 301 (that is, between the flow on / off valve 52a and the orifice 55a, between the orifice 55a and the filter 57, between the filter 57 and the flow on / off valve 52b, and the flow on / off valve 52b). The heater H is shown between the processing container 301 and the processing container 301), but the heater H may be provided at another location including the processing container 301 and the supply line on the downstream side of the processing container 301. Therefore, the heater H may be provided in all the flow paths until the processing fluid supplied from the fluid supply tank 51 is discharged to the outside. Further, in particular, from the viewpoint of adjusting the temperature of the processing fluid supplied to the processing container 301, the heater H is provided at a position where the temperature of the processing fluid flowing upstream of the processing container 301 can be adjusted. preferable.

Further, a safety valve 56a is provided between the orifice 55a and the filter 57, a safety valve 56b is provided between the processing container 301 and the distribution on / off valve 52f, and a safety valve 56b is provided between the concentration measurement sensor 60 and the distribution on / off valve 52g. Is provided with a safety valve 56c. These safety valves 56a to 56c play a role of communicating the supply line to the outside and urgently discharging the fluid in the supply line to the outside in the event of an abnormality such as when the pressure in the supply line becomes excessive.

FIG. 4 is a block diagram showing a functional configuration of the control unit 4. The control unit 4 receives measurement signals from various elements shown in FIG. 3 and transmits control instruction signals to various elements shown in FIG. For example, the control unit 4 receives the measurement results of the pressure sensors 53a to 53e, the temperature sensors 54a to 54g, and the concentration measurement sensor 60. Further, the control unit 4 transmits a control instruction signal to the distribution on / off valves 52a to 52j, the exhaust adjustment valve 59, and the exhaust adjustment needle valves 61a to 61b. The signals that can be transmitted and received by the control unit 4 are not particularly limited. For example, when the safety valves 56a to 56c can be opened and closed based on the control instruction signal from the control unit 4, the control unit 4 transmits the control instruction signal to the safety valves 56a to 56c as needed. However, when the opening / closing drive method of the safety valves 56a to 56c does not depend on signal control, the control unit 4 does not transmit the control instruction signal to the safety valves 56a to 56c.

[Supercritical drying treatment]
Next, the drying mechanism of IPA using the processing fluid in the supercritical state will be described.

FIG. 5 is a diagram for explaining the drying mechanism of the IPA, and is an enlarged cross-sectional view simply showing a pattern P as a recess of the wafer W.

When the processing fluid R in the supercritical state was introduced into the container body 311 of the processing container 301 in the supercritical processing apparatus 3, only IPA was filled between the patterns P as shown in FIG. 5A. There is.

The IPA between the patterns P gradually dissolves in the processing fluid R by coming into contact with the processing fluid R in the supercritical state, and gradually replaces the processing fluid R as shown in FIG. 5 (b). At this time, in addition to the IPA and the processing fluid R, a mixed fluid M in a state in which the IPA and the processing fluid R are mixed exists between the patterns P.

Then, as the replacement of the IPA with the processing fluid R progresses between the patterns P, the IPA is removed from between the patterns P, and finally, as shown in FIG. 5 (c), the processing fluid R in the supercritical state. Only the pattern P is filled.

After the IPA is removed from between the patterns P, the pressure in the container body 311 is lowered to the atmospheric pressure, so that the processing fluid R changes from the supercritical state to the gas state as shown in FIG. 5 (d), and the pattern Between P is occupied only by gas. In this way, the IPA between the patterns P is removed, and the drying process of the wafer W is completed.

Against the background of the mechanisms shown in FIGS. 5A to 5D described above, the supercritical processing apparatus 3 of the present embodiment performs the IPA drying treatment as follows.

That is, the substrate processing method performed by the supercritical processing apparatus 3 includes a step of carrying the wafer W in which the pattern P is filled with IPA for preventing drying into the container body 311 of the processing container 301, and a fluid supply unit (that is, a fluid). The process of supplying the processing fluid in the supercritical state into the container body 311 via the supply tank 51, the flow on / off valve 52a, the flow on / off valve 52b, and the fluid supply header 317), and the IPA from the wafer W in the container body 311. The drying process for removing is provided with a step of performing the drying process using a processing fluid in a supercritical state.

In particular, in the drying treatment of IPA using the processing fluid in the supercritical state (that is, the supercritical drying treatment), the container body 311 of the processing container 301 is maintained so as to maintain a high pressure that does not cause gas-liquid separation between the patterns P. The processing fluid is supplied and discharged. More specifically, a step of lowering the pressure in the container body 311 by discharging the processing fluid from the inside of the container body 311 and a pressure reduction step in the container body 311 by supplying the processing fluid into the container body 311. The IPA between the patterns P of the wafer W is gradually removed by alternately repeating the step of raising the pressure a plurality of times. In the boosting step, the processing fluid is supplied into the container body 311 so that the pressure between the patterns P is higher than the maximum value of the critical pressure of the two-component system of the processing fluid and the IPA. On the other hand, in the step-down step, as the step-down step and the step-up step are repeated to reduce the IPA concentration in the mixed fluid between the patterns P and increase the processing fluid concentration, the pressure between the patterns P gradually decreases. The fluid is discharged from the container body 311 so as to be. However, even in this step-down step, the pressure between the patterns P is maintained at a pressure at which the fluid between the patterns P maintains a non-gas state.

A typical example of drying treatment is shown below. In each of the following drying treatment examples, CO ₂ is used as the treatment fluid.

[First example of drying treatment]
FIG. 6 is a diagram showing an example of the relationship between the time in the first drying treatment example, the pressure in the treatment container 301 (that is, in the container body 311), and _{the consumption amount of the treatment fluid (CO 2).} The curve A shown in FIG. 6 represents the relationship between the time (horizontal axis; sec (seconds)) and the pressure in the processing container 301 (vertical axis; MPa) in the first drying treatment example. The curve B shown in FIG. 6 shows the relationship between the time (horizontal axis; sec (seconds)) and _{the consumption amount of the processing fluid (CO 2} ) (vertical axis; kg (kilograms)) in the first drying treatment example.

_{In this drying treatment example, first, the fluid introduction step T1 is performed, and CO 2} is supplied from the fluid supply tank 51 into the processing container 301 (that is, in the container body 311).

In the fluid introduction step T1, the control unit 4 opens the distribution on / off valve 52a, the distribution on / off valve 52b, the distribution on / off valve 52c, and the distribution on / off valve 52f shown in FIG. Control is performed so that the valve is closed. Further, the control unit 4 controls so that the distribution on / off valves 52g to 52i are in the open state and the distribution on / off valves 52j are in the closed state. Further, the control unit 4 controls the exhaust adjustment needle valves 61a to 61b so as to be in the open state. Further, the control unit 4 adjusts the opening degree of the exhaust adjustment valve 59, and the pressure in the processing container 301 is a desired pressure (in the example shown in FIG. 6) so that _{the CO 2 in the processing container 301 can maintain the supercritical state.} It is adjusted to 15 MPa).

In the fluid introduction step T1 shown in FIG. 6, the IPA on the wafer W begins to dissolve in _{CO 2 in the supercritical state in the processing container 301.} When CO _{2 in the} supercritical state and IPA on the wafer W start to be mixed, IPA and CO ₂ are locally in various ratios in _{the mixed fluid of CO 2 and IPA, and the critical pressure of CO 2} is also locally in various values. Can be. On the other hand, in the fluid introduction step T1, the supply pressure _{of CO 2 into the processing container 301 is adjusted to a pressure higher than all the critical pressures of CO 2} (that is, a pressure higher than the maximum value of the critical pressure). Therefore, regardless of the ratio of IPA and CO ₂ mixed fluid, CO ₂ in the processing chamber 301 is brought into a supercritical state or a liquid state, not a gaseous state.

Then, after the fluid introduction step T1, the fluid holding step T2 is performed, and the IPA concentration and the CO ₂ concentration of the mixed fluid between the patterns P of the wafer W are desired concentrations (for example, the IPA concentration is 30% or less and the CO ₂ concentration is 70%). The pressure in the processing container 301 is kept constant until the above) is reached.

In this fluid holding step T2, _{the pressure inside the processing container 301 is adjusted to such an extent that CO 2} in the processing container 301 can maintain a supercritical state, and in the example shown in FIG. 6, the pressure inside the processing container 301 is 15 MPa. It is kept. In the fluid holding step T2, the control unit 4 controls so that the distribution on / off valve 52b and the distribution on / off valve 52f shown in FIG. 3 are closed, and the supply and discharge of _{CO 2 into the processing container 301 are stopped.} NS. The open / closed state of the other various valves is the same as the open / closed state in the above-mentioned fluid introduction step T1.

Then, after the fluid holding step T2, the fluid supply / discharge step T3 is performed to discharge the fluid from the processing container 301 to lower the pressure inside the processing container 301, and _{to supply CO 2} into the processing container 301 for processing. The step of boosting the pressure inside the container 301 is repeated.

In the step-down step, _{a fluid in which CO 2} and IPA are mixed is discharged from the processing container 301. On the other hand, in the boosting step, fresh CO ₂ containing no IPA is supplied from the fluid supply tank 51 to the processing container 301. In this way, while actively discharging IPA from the processing container 301 in the step-down step, CO ₂ containing no IPA is supplied into the processing container 301 in the step-up step, thereby promoting the removal of IPA from the wafer W. Will be done.

The number of repetitions of the step-down step and the step-up step in the fluid supply / discharge step T3 is not particularly limited, but the drying process of this example is at least the following first process steps S1 and second treatment steps at the start of the fluid supply / discharge step T3. It has S2. The control unit 4 controls the fluid supply unit (that is, the distribution on / off valves 52a to 52b shown in FIG. 3) and the fluid discharge unit (that is, the distribution on / off valves 52f to 52j and the exhaust adjustment valve 59 shown in FIG. 3). The drying treatment including the first treatment step S1 and the second treatment step S2 is performed using _{CO 2 in a supercritical state.}

That is, in the first processing step S1 performed immediately after the above-mentioned fluid holding step T2, until the inside of the processing container 301 reaches the first discharge ultimate pressure Pt1 (for example, 14 MPa) in which the vaporization _{of CO 2 in the supercritical state does not occur.} The fluid in the processing container 301 is discharged, and then the inside of the processing container 301 reaches the first supply ultimate pressure Ps1 (for example, 15 MPa) which _{is higher than the first discharge ultimate pressure Pt1 and CO 2 in the processing container 301 does not vaporize. CO 2} is supplied into the processing container 301 until

On the other hand, in the second treatment step S2 performed immediately after the first treatment step S1 described above, the second discharge ultimate pressure Pt2 in which the vaporization _{of CO 2 in the supercritical state does not occur after the first treatment step S1 is the second.} The fluid in the processing container 301 is discharged until the inside of the processing container 301 reaches a second discharge ultimate pressure Pt2 (for example, 13 MPa) different from the discharge ultimate pressure Pt1 of 1, and then the fluid is discharged higher than the second discharge ultimate pressure Pt2. _{CO 2} is supplied into the processing container 301 until the inside of the processing container 301 is filled with the second supply ultimate pressure Ps2 (for example, 15 MPa) at which the vaporization _{of CO 2} in the processing container 301 does not occur.

In particular, in this drying treatment example, the first discharge ultimate pressure Pt1 in the step-down step of the first treatment step S1 is set higher than the second discharge ultimate pressure Pt2 in the step-down step of the second treatment step S2. (That is, "Pt1> Pt2" is satisfied).

FIG. 7 is _{a graph showing the relationship between the CO 2} concentration, the critical temperature, and the critical pressure. The horizontal axis of FIG. 7 indicates _{the critical temperature of CO 2} (K: Kelvin) and the CO ₂ concentration (%), and the vertical axis of FIG. 7 indicates the critical pressure of _{CO 2 (MPa).} Note the CO ₂ concentration in FIG. 7 represents the mixing ratio of CO _2, the CO ₂ concentration is represented by the percentage of CO ₂ in the mixed gas of IPA and CO _2.

The curve C in FIG. 7 _{shows the relationship between the CO 2} concentration, the critical temperature and the critical pressure, and when the CO ₂ state is above the curve C, the CO ₂ has a pressure higher than the critical pressure, and the CO _When the state of 2 is above the curve C, it indicates that CO ₂ has a pressure lower than the critical pressure.

In this drying process example as described above, the step-down step of reducing the pressure in the processing container 301 from the processing chamber 301 by discharging the CO _2, the process of CO ₂ from the fluid supply tank 51 container 301 (i.e. the container main body 311) The IPA on the wafer W is gradually removed by repeatedly performing the step of increasing the pressure inside the processing container 301 by introducing it into the container. In this drying process, in each step of increasing the pressure, the supply pressure _{of CO 2 to} the processing container 301 is set to a pressure higher than the maximum value of the critical pressure of _{CO 2.} Therefore, the first supply ultimate pressure Ps1 and the second supply ultimate pressure Ps2 described above are higher than all critical pressures represented by, for example, the curve C in FIG. 7 (that is, higher than the maximum value of the critical pressure of _{CO 2).} It is adjusted to a high pressure (for example, 15 MPa). This makes it possible to prevent the vaporization _{of CO 2} in the processing container 301.

CO ₂ and IPA in a fluid mixture of CO ₂ and IPA as described above is present in locally varying proportions, the critical pressure of CO ₂ also can be a locally different values. However, in this embodiment, since the supply pressure of the CO ₂ into the processing vessel 301 is adjusted to a pressure higher than the maximum value of the critical pressure of CO _2, regardless of the ratio of IPA and CO ₂ mixed fluid, pattern _{CO 2} between P is in a supercritical state or a liquid state, and is not in a gaseous state.

On the other hand, in the step-down step, _{CO 2} is discharged _{from the processing container 301 so that the CO 2} between the patterns P has a pressure higher than the critical pressure. That is, the pressure inside the processing container 301 (exhaust ultimate pressure) in each step-down step is adjusted to a pressure higher than the critical pressure of _{CO 2.} In general, as the removal of IPA between patterns P progresses, the IPA concentration in the mixed fluid between patterns P _{tends to gradually decrease and the CO 2} concentration tends to gradually increase. On the other hand, as it is clear from the curve C of FIG. 7, when the critical pressure of CO ₂ varies depending on the concentration of CO _2, greater than, especially CO ₂ concentrations approximately 60%, CO ₂ The critical pressure gradually decreases as the concentration of carbon dioxide increases.

Further, the larger the difference between the pressure in the processing container 301 in the pressure increasing step (that is, the ultimate supply pressure) and the pressure in the processing container 301 in the lowering step (that is, the ultimate discharge pressure), the larger the amount of fluid discharged from the processing container 301. Increase. As the amount of fluid discharged from the processing container 301 increases, the amount of IPA discharged from the processing container 301 increases, and the amount of _{CO 2 supplied into the processing container 301 can be increased in the subsequent boosting step.} can. Therefore, the larger the pressure difference in the processing container 301 between the continuously step-down step and the step-up step, the more _{effectively the replacement of IPA with CO 2} can be promoted, and the shorter the drying process of IPA is. It will be possible to do it in time.

In the plurality of step-down steps repeatedly performed in the fluid supply / discharge step T3 shown in FIG. 6 _{, the pattern is within a range in which the CO 2} between the patterns P is maintained in a non-gas state based on the relationship between _{the CO 2 concentration and the critical pressure described above.} The pressure of CO ₂ between P is gradually reduced to gradually increase the amount _{of CO 2} emitted from the processing container 301.

For example, in the first processing step S1 shown in FIG. 6, assuming that the CO ₂ concentration of the mixed fluid between the patterns P is 70%, _{the critical pressure of CO 2} between the patterns P is indicated by the point C70 in FIG. As described above, the pressure is generally lower than 14 MPa. Therefore, the first discharge ultimate pressure Pt1 in the step-down step of the first treatment step S1 is set to a pressure higher than the critical pressure indicated by the point C70 in FIG. 8 (for example, 14 MPa). As a result, the fluid can be discharged from the processing container 301 in a state where _{CO 2} between the patterns P is prevented from being vaporized in the step-down step of the first processing step S1.

On the other hand, assuming that the CO ₂ concentration of the mixed fluid between the patterns P is 80% in _{the second treatment step S2 performed thereafter, the critical pressure of CO 2} between the patterns P is indicated by the point C80 in FIG. As described above, it is about 12 MPa. Therefore, the second discharge ultimate pressure Pt2 in the step-down step of the second treatment step S2 is set to a pressure higher than the critical pressure indicated by the point C80 in FIG. 9 (for example, 13 MPa). As a result, the fluid can be discharged from the processing container 301 in a state where _{CO 2} between the patterns P is prevented from being vaporized in the step-down step of the second processing step S2. In particular, since the amount of fluid discharged in the step-down step of the second treatment step S2 is larger than the amount of fluid discharged in the step-down step of the first treatment step S1, IPA is removed more effectively in the second treatment step S2. It is possible.

In the example shown in FIG. 6, the pressure in the processing container 301 in each boosting step is raised to the same pressure (that is, 15 MPa), but the pressure in the processing vessel 301 does not necessarily have to be the same between the boosting steps. However, pressure in the processing container 301 in the boosting step is increased to a pressure higher than the maximum value of the critical pressure of CO _2, CO ₂ in the processing chamber 301 keeps the non-gaseous state.

Further, in the example shown in FIG. 6, the pressure in the processing container 301 in the step-down step is gradually lowered so as to be gradually lowered, but it is not always necessary to gradually lower the pressure in the processing container 301 in the step-down step. No. However, from the viewpoint of removing IPA in a short time, it is preferable that the amount of fluid discharged from the processing container 301 in the step-down step is large, and the lower the pressure in the processing container 301 in the step-down step, the greater the amount of fluid discharged from the processing container 301. The amount of fluid discharged is large. _{Therefore, considering that the CO 2} concentration of the mixed fluid between the patterns P gradually increases with the progress of the fluid supply / discharge step T3 and the characteristic of the critical temperature-critical pressure of _{CO 2} shown in FIG. 7, the treatment in the step-down step It is preferable that the pressure in the container 301 is gradually lowered so as to be gradually lowered.

_{In the example shown in FIG. 6, when CO 2} is supplied into the processing container 301 up to the first supply ultimate pressure Ps1 (15 MPa) in the boosting step of the first processing step S1, the IPA concentration between the patterns P is diluted. It will soon be less than 20%. Therefore, immediately after the step of increasing the pressure of the first processing step S1, the step of lowering the pressure of the second processing step S2 is performed, and the fluid is discharged from the processing container 301. Further, in the treatment steps after the first treatment step S1, the step-down step and the step-up step are also performed in the same manner, each step-down step is started immediately after the immediately preceding step-up step is completed, and each step-up step is completed immediately before the step-down step. It will start immediately after.

The step-down step and the step-up step are performed by the control unit 4 controlling the opening and closing of the distribution on / off valve 52b, the distribution on / off valve 52f, and the exhaust adjustment valve 59 shown in FIG. For example, when CO ₂ is supplied into the processing container 301 to perform the boosting step, the distribution on / off valve 52b is opened and the distribution on / off valve 52f is closed under the control of the control unit 4. On the other hand, when CO ₂ is discharged from the processing container 301 to perform the step-down step, the distribution on / off valve 52b is closed and the distribution on / off valve 52f is opened under the control of the control unit 4. In this step-down step, the exhaust adjustment valve 59 is controlled by the control unit 4 in order to discharge the fluid in the processing container 301 to exactly the desired discharge ultimate pressure.

In particular, the control unit 4 opens the exhaust adjustment valve 59 based on the measurement result of the pressure sensor 53d provided between the processing container 301 and the distribution on / off valve 52f in order to perform strict control in the step-down process. To adjust. That is, the pressure in the supply line communicating with the inside of the processing container 301 is measured by the pressure sensor 53d. The control unit 4 obtains the opening degree of the exhaust gas adjusting valve 59 necessary for adjusting the inside of the processing container 301 to a desired pressure from the measured value of the pressure sensor 53d, and realizes the obtained opening degree. A control instruction signal is sent to the exhaust adjustment valve 59. The exhaust gas adjusting valve 59 adjusts the opening degree based on the control instruction signal from the control unit 4, and the inside of the processing container 301 is adjusted to a desired pressure. As a result, the pressure in the processing container 301 is accurately adjusted to a desired pressure.

In this way, the control unit 4 controls the supply amount and the discharge amount _{of CO 2 to} the processing container 301 in the process in which the above-mentioned step-down step and step-up step are repeatedly performed, _{and the CO 2} between the patterns P is always higher than the critical pressure. Have high pressure. _{As a result, it is possible to prevent the CO 2} between the patterns P from being vaporized, and the CO ₂ between the patterns P is always in a non-gas state during the fluid supply / discharge step T3. The pattern collapse that can occur in the wafer W is due to the gas-liquid interface that can exist between the patterns P, and in general, the gas processing fluid (CO _{2 in} this example) comes into contact with the liquid IPA between the patterns P. Caused by that. According to this drying treatment example, while the fluid supply / discharge step T3 is being performed, the CO ₂ between the patterns P is always in a non-gas state as described above, so that the pattern collapse does not occur in principle.

It is difficult to directly measure the concentration _{of CO 2} between patterns P while the fluid supply / discharge step T3 is being performed. Therefore, the timing of performing the step-down step and the step-up step may be determined based on the result of the experiment conducted in advance, and the step-down step and the step-up step may be performed based on the determined timing. For example, the timing at which the fluid in the processing container 301 is discharged until the inside of the processing container 301 reaches the first discharge reaching pressure Pt1 in the step-down step of the first processing step S1, and the second step in the step-down step of the second processing step S2. At least one of the timings for discharging the fluid in the processing container 301 until the discharge ultimate pressure Pt2 is filled in the processing container 301 can be determined based on the results of experiments performed in advance.

Further, _{it is preferable that the temperature of CO 2 in} the processing container 301 is adjusted to a temperature at which _{CO 2} can maintain a supercritical state by a heater (not shown) provided in the processing container 301. In this case, it is preferable that such a heater is controlled by the control unit 4 based on the measurement result of the temperature sensor 54e that measures the temperature of the fluid in the processing container 301, and the heating temperature of the heater is adjusted. However, the temperature of the fluid in the processing container 301 does not necessarily have to be adjusted under the control of the control unit 4. _{Even if the temperature of CO 2} in the processing container 301 becomes equal to or lower than the critical temperature, the CO ₂ in the processing container 301 is in a non-gas state such as a liquid. Therefore, the pattern collapse caused by the gas-liquid interface between the patterns P _{does not occur even if the temperature of CO 2} in the processing container 301 becomes equal to or lower than the critical temperature. However, the temperature of CO ₂ in the processing chamber 301, because it is one of the factors affecting the CO ₂ density, from the viewpoint of improving the displacement efficiency of the IPA to CO _2, CO ₂ in the processing chamber 301 It is preferable to positively adjust the temperature of the carbon dioxide by a device such as a heater.

_{Then, the IPA between the patterns P is replaced with CO 2} by the above-mentioned fluid supply / discharge step T3, and the IPA remaining in the processing container 301 is sufficiently reduced (for example, the IPA concentration in the processing container 301 is 0% to several). The fluid discharge step T4 is performed when the percentage reaches%), and the inside of the processing container 301 is returned to atmospheric pressure. _{As a result, CO 2} can be vaporized while preventing the IPA remaining in the processing container 301 from reattaching to the wafer W, and as shown in FIG. 5 (d), only gas is left between the patterns P. exist.

In the fluid discharge step T4, the control unit 4 closes the distribution on / off valves 52a to 52e shown in FIG. 3, opens the exhaust adjustment valve 59, opens the distribution on / off valves 52f to 52i, and opens the distribution on / off valves 52j. Is closed, and the exhaust adjusting needle valves 61a to 61b are controlled to be open.

By performing the fluid introduction step T1, the fluid holding step T2, the fluid supply / discharge step T3, and the fluid discharge step T4 as described above, the drying process for removing the IPA from the wafer W is completed.

The timing at which each of the fluid introduction step T1, the fluid holding step T2, the fluid supply / discharge step T3 and the fluid discharge step T4 is performed, the duration of each step, and the repetition of the step-down step and the boosting step in the fluid supply / discharge step T3. The number of times, etc. may be determined by any method. The control unit 4 determines the timing at which each process is performed, the duration of each process, and the fluid supply according to, for example, the "IPA concentration contained in the fluid discharged from the processing container 301" measured by the concentration measurement sensor 60. The number of repetitions of the step-down step and the step-up step in the discharge step T3 may be determined. Further, the control unit 4 may determine the timing at which each step is performed, the duration of each step, the number of repetitions of the step-down step and the step-up step in the fluid supply / discharge step T3, and the like, based on the results of experiments performed in advance. good.

According to the above-mentioned supercritical processing device 3 (that is, the substrate processing device) and the substrate processing method, the drying process of removing the liquid from the substrate using the processing fluid in the supercritical state can be performed in a short time while suppressing the consumption of the processing fluid. It can be done with, and the occurrence of pattern collapse can be effectively prevented.

According to the present inventor's experiments, based on the prior art, IPA on the wafer W by continuously supplying and discharging per minute 0.5kg of CO ₂ in the supercritical state of 10MPa to the processing chamber 301 It took about 30 minutes to dry the wafer, and it was necessary to consume _{several tens of kg of CO 2.} On the other hand, when the IPA on the wafer W is removed based on the present drying treatment example as shown in FIG. 6, in the fluid supply / discharge step T3, "a treatment step having one step of lowering the pressure and one step of raising the pressure". The wafer W could be appropriately dried by repeating the above 7 times, the total processing time was about 7 minutes, and the CO ₂ consumption was about 1.7 kg. As described above, the substrate processing apparatus and the substrate processing method of the present embodiment _{can dramatically promote the shortening of the processing time and the reduction of the consumption of CO 2} (processing fluid).

[Second example of drying treatment]
FIG. 10 is a diagram showing the time and the pressure in the processing container 301 in the second drying treatment example. The curve A shown in FIG. 10 represents the relationship between the time (horizontal axis; sec) and the pressure in the processing container 301 (vertical axis; MPa) in the second drying treatment example.

In this drying treatment example, detailed description of the same or similar contents as the above-mentioned first drying treatment example will be omitted.

In this drying treatment example as well, similarly to the first drying treatment example described above, the fluid introduction step T1, the fluid holding step T2, the fluid supply / discharge step T3, and the fluid discharge step T4 are sequentially performed. However, in the fluid supply / discharge step T3 of this drying treatment example, the first discharge reaching pressure Pt1 in the step-down step of the first treatment step S1 performed immediately after the fluid holding step T2 is the step-down step of the second treatment step S2 thereafter. It is lower than the second discharge ultimate pressure Pt2 in.

In the fluid supply / discharge step T3 of the present drying treatment, the step-down step and the step-up step of the third treatment step S3 performed immediately after the second treatment step S2 are performed as follows. That is, after the second treatment step S2, the treatment container reaches the third discharge ultimate pressure Pt3, which is the third discharge ultimate pressure Pt3 in which the vaporization _{of CO 2 in the supercritical state does not occur, and is lower than the second discharge ultimate pressure Pt2.} The fluid in the processing container 301 is discharged until the inside of the 301 is filled. _{After that, CO 2} is supplied into the processing container 301 until the third supply reaching pressure Ps3, which is higher than the third discharge reaching pressure Pt3 and CO _{2 in the processing container 301 does not vaporize, becomes inside the processing container 301.} ..

The third supply ultimate pressure Ps3 is set to the same pressure as the first supply ultimate pressure Ps1 and the second supply ultimate pressure Ps2, and can be set to 15 MPa as in the above-mentioned first drying treatment example, for example. Is.

In this drying treatment example, the lamp-up type drying treatment is performed, and among the step-down steps of the fluid supply / discharge step T3, the discharge reaching pressure (that is, reaching the first discharge) in the step-down step of the first treatment step S1 performed first. The pressure Pt1) shows the lowest pressure. That is, among the step-down steps of the fluid supply / discharge step T3, the largest amount of fluid is discharged from the processing container 301 in the step-down step of the first processing step S1. This makes it possible to efficiently remove the IPA on the film formed above the pattern P of the wafer W.

FIG. 11 is a cross-sectional view for explaining the state of the IPA liquid-filled on the pattern P of the wafer W.

An IPA film having a thickness of D1 is formed on the pattern P of the wafer W carried into the supercritical processing apparatus 3. The thickness D1 of this IPA film is much larger than the thickness D2 of the pattern P, and the thickness D1 is generally about several tens of times the thickness D2. The portion of the IPA film above the pattern P also needs to be removed by the supercritical processing apparatus 3, but the amount of IPA film removed above the pattern P is much larger than the amount of IPA removed between the patterns P. growing. Further, the IPA between the patterns P can be removed only after the portion of the IPA film above the pattern P is removed.

Therefore, in the fluid supply / discharge step T3, the IPA film above the pattern P is first removed as much as possible by the first treatment step S1, and the IPA between the patterns P is removed by the second treatment step S2 and the subsequent treatment steps. It is preferable to do so. Therefore, in this drying treatment example, first, in the first treatment step S1, a large amount of fluid is discharged from the treatment container 301 in the step-down step, and a large amount of CO ₂ is supplied to the treatment container 301 in the pressurization step, which is above the pattern P. The IPA film is significantly removed.

When removing the IPA film above the pattern P, there is no concern that the pattern will collapse because the IPA is filled between the patterns P. However, considering the possibility that not only the IPA film above the pattern P but also a part of the IPA between the patterns P is removed in the first treatment step S1, the first discharge in the step-down step of the first treatment step S1. The ultimate pressure Pt1 is set to a pressure higher than the critical pressure _{of CO 2 in the processing container 301.}

The step-down step and the step-up step in the treatment steps other than the first treatment step S1 are performed in the same manner as in the above-mentioned first drying treatment example. That is, the pressure in the processing container 301 in each boosting step of the fluid supply / discharge step T3 _{is higher than the maximum value of the critical pressure of CO 2} and is raised to the same pressure (that is, 15 MPa). Further, in the second processing step S2 of the fluid supply / discharge process T3 and the step-down step in the subsequent processing steps, the pressure in the processing container 301 is gradually lowered. However, the pressure between the patterns P in each step-down step _{is maintained at a pressure at which CO 2} between the patterns P remains in a non-gas state.

As described above, according to the present drying treatment example, the IPA film formed above the pattern P of the wafer W can be efficiently removed, and the processing time of the IPA drying treatment can be shortened.

[Third drying treatment example]
FIG. 12 is a diagram showing the time and the pressure in the processing container 301 in the third drying treatment example. The curve A shown in FIG. 12 represents the relationship between the time (horizontal axis; sec) and the pressure in the processing container 301 (vertical axis; MPa) in the third drying treatment example.

In this drying treatment example, detailed description of the same or similar contents as the above-mentioned first drying treatment example will be omitted.

In this drying treatment example as well, similarly to the first drying treatment example described above, the fluid introduction step T1, the fluid holding step T2, the fluid supply / discharge step T3, and the fluid discharge step T4 are sequentially performed. However, in the fluid supply / discharge step T3 of this drying treatment example, a pressure holding step for maintaining the pressure in the processing container 301 to be substantially constant is performed between the step-down step and the step-pressing step.

In each pressure holding step, the inside of the processing container 301 is held at the same pressure as the discharge ultimate pressure of the pressure reducing step performed immediately before.

By performing such a pressure holding step, IPA can be efficiently removed from the wafer W.

The present invention is not limited to the above-described embodiments and modifications, but may include various aspects to which various modifications that can be conceived by those skilled in the art are added, and the effects produced by the present invention are also described above. It is not limited to the matters of. Therefore, various additions, changes, and partial deletions can be made to the scope of claims and each element described in the specification without departing from the technical idea and purpose of the present invention.

For example, the treatment fluid used for the drying treatment may be _{a fluid other than CO 2} , and any fluid capable of removing the drying prevention liquid filled in the recesses of the substrate in a supercritical state is used as the treatment fluid. be able to. Further, the anti-drying liquid is not limited to IPA, and any liquid that can be used as the anti-drying liquid can be used.

Further, in the above-described embodiments and modifications, the present invention is applied to the substrate processing apparatus and the substrate processing method, but the application target of the present invention is not particularly limited. For example, the present invention is also applicable to a program for causing a computer to execute the above-mentioned substrate processing method, and a computer-readable non-temporary recording medium on which such a program is recorded.

3 Supercritical processing device 4 Control unit 51 Fluid supply tank 52a to 52j Flow on / off valve 59 Exhaust adjustment valve 301 Processing container P pattern Ps1 First supply ultimate pressure Ps2 Second supply ultimate pressure Pt1 First discharge ultimate pressure Pt2 First Discharge ultimate pressure of 2 S1 First processing step S2 Second processing step W Wafer

Claims (7)

A substrate processing method in which a drying process for removing a liquid from a substrate in a processing container is performed using a processing fluid in a supercritical state.
The fluid in the processing container is discharged until the inside of the processing container reaches the first discharge ultimate pressure at which the vaporization of the supercritical processing fluid existing in the treatment container does not occur, and then the first discharge is performed. The first supply step of supplying the processing fluid into the processing container until the inside of the processing container reaches the first supply ultimate pressure higher than the ultimate pressure and the vaporization of the processing fluid in the processing container does not occur.
After the first treatment step, to discharge the fluid in the processing chamber to the processing chamber is a second discharge reaching pressure of vaporization of the process fluid in a supercritical state does not occur, then the second A second processing step of supplying the processing fluid into the processing container until the inside of the processing container reaches a second supply reaching pressure higher than the discharge ultimate pressure and the vaporization of the processing fluid in the processing container does not occur.
After the second treatment step, the fluid in the treatment container is discharged until the inside of the treatment container reaches a third discharge ultimate pressure at which the vaporization of the treatment fluid in the supercritical state does not occur, and then the third discharge is performed. A third processing step of supplying the processing fluid into the processing container until the inside of the processing container reaches a third supply reaching pressure higher than the ultimate pressure and the vaporization of the processing fluid in the processing container does not occur. Yes, and
The substrate processing method in which the first discharge ultimate pressure is lower than the second discharge ultimate pressure and the third discharge ultimate pressure. Immediately after the first treatment step, the second treatment step is performed,
The substrate processing method according to claim 1, wherein the third processing step is performed immediately after the second processing step. The substrate processing method according to claim 2, wherein the third discharge ultimate pressure is lower than the second discharge ultimate pressure. A fluid supply / discharge step in which a step of lowering the pressure inside the treatment container and a step of raising the pressure inside the treatment container are repeated within a range in which the pressure in the treatment container is higher than the critical pressure of the treatment fluid. Including a fluid supply / discharge step having a fluid supply / discharge step including a first treatment step, the second treatment step, and the third treatment step.
6. Substrate processing method. In at least one of the first treatment step, the second treatment step, and the third treatment step, the step of stepping down the pressure inside the treatment container and the step of raising the pressure inside the treatment container are described as described above. The substrate processing method according to any one of claims 1 to 4, wherein a pressure holding step of maintaining the pressure in the processing container at a substantially constant level is performed. A processing container that is a substrate having a recess and in which a substrate filled with a liquid is carried into the recess.
A fluid supply unit that supplies a supercritical processing fluid into the processing container,
A fluid discharge unit that discharges the fluid in the processing container and
A control unit that controls the fluid supply unit and the fluid discharge unit and performs a drying process for removing the liquid from the substrate in the processing container using the processing fluid in a supercritical state is provided.
The control unit controls the fluid supply unit and the fluid discharge unit, and controls the fluid supply unit and the fluid discharge unit.
The fluid in the processing container is discharged until the inside of the processing container reaches the first discharge ultimate pressure at which the vaporization of the supercritical processing fluid existing in the treatment container does not occur, and then the first discharge is performed. The first supply step of supplying the processing fluid into the processing container until the inside of the processing container reaches the first supply ultimate pressure higher than the ultimate pressure and the vaporization of the processing fluid in the processing container does not occur.
After the first treatment step, to discharge the fluid in the processing chamber to the processing chamber is a second discharge reaching pressure of vaporization of the process fluid in a supercritical state does not occur, then the second A second processing step of supplying the processing fluid into the processing container until the inside of the processing container reaches a second supply reaching pressure higher than the discharge ultimate pressure and the vaporization of the processing fluid in the processing container does not occur.
After the second treatment step, the fluid in the treatment container is discharged until the inside of the treatment container reaches a third discharge ultimate pressure at which the vaporization of the treatment fluid in the supercritical state does not occur, and then the third discharge is performed. A third processing step of supplying the processing fluid into the processing container until the inside of the processing container reaches a third supply reaching pressure higher than the ultimate pressure and the vaporization of the processing fluid in the processing container does not occur. There line,
The substrate processing apparatus in which the first discharge ultimate pressure is lower than the second discharge ultimate pressure and the third discharge ultimate pressure. A computer-readable recording medium in which a program for causing a computer to execute a substrate processing method in which a drying process for removing a liquid from a substrate in a processing container is performed using a processing fluid in a supercritical state is recorded.
The substrate processing method is
The fluid in the processing container is discharged until the inside of the processing container reaches the first discharge ultimate pressure at which the vaporization of the supercritical processing fluid existing in the treatment container does not occur, and then the first discharge is performed. The first supply step of supplying the processing fluid into the processing container until the inside of the processing container reaches the first supply ultimate pressure higher than the ultimate pressure and the vaporization of the processing fluid in the processing container does not occur.
After the first treatment step, to discharge the fluid in the processing chamber to the processing chamber is a second discharge reaching pressure of vaporization of the process fluid in a supercritical state does not occur, then the second A second processing step of supplying the processing fluid into the processing container until the inside of the processing container reaches a second supply reaching pressure higher than the discharge ultimate pressure and the vaporization of the processing fluid in the processing container does not occur.
After the second treatment step, the fluid in the treatment container is discharged until the inside of the treatment container reaches a third discharge ultimate pressure at which the vaporization of the treatment fluid in the supercritical state does not occur, and then the third discharge is performed. A third processing step of supplying the processing fluid into the processing container until the inside of the processing container reaches a third supply reaching pressure higher than the ultimate pressure and the vaporization of the processing fluid in the processing container does not occur. Yes, and
The first discharge ultimate pressure is lower than the second discharge ultimate pressure and the third discharge ultimate pressure .

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